Apparatus for discharging liquefied gases from a vessel below atmospheric temperature



55% Q I V H II I Dec. 1, 1936. w. L. DE BAUFRE APPARATUS FOR DISCHARGING LIQUEFIED GASES FROM A VESSEL BELOW ATMOSPHERIC TEMPERATURE Filed Aug. 12, 1935 4% INVENTOR.

Patented Dec. 1, 193

UNITED STATES APPARATUS FOR. GASES FROM DISCHARGING LIQUEFIED A VESSEL BELOW ATMOS- PHERIC TEMPERATURE William Lane De Baufre, Lincoln, Nebr.

Application August 12,

18 Claim.

This invention relates to the art of automatically controlling the discharge of liquefied gases from a vessel below atmospheric temperature in order to maintain a nearly constant liquid .level therein. It is particularly applicable to plants for rectifying atmospheric air into more or less pure'oxygen and nitrogen. In the air separation plant described in U. S. Patent No. 1,951,185, issued March 13, 1934, for example, there are two places where the liquid level should be maintained as nearly constant as possible by discharging liquefied gases therefrom. These places-are the pot E at the lower end of preliminary tray section F and the pot at the lower end of exchanger K. Heretofore, the liquefied gases in these pots have been discharged through manually controlled valves 3| and 44 respectively. Automatic control of the discharge of these liquefied gases would eliminate the necessity of manual control and would also maintain conditions of operation more nearly constant. As the effectiveness of rectification is increased by more nearly constant conditions of operation, such auto- .matic means would be an improvement over manual control in increasing the purities of the products of rectification. p

In applying such automatic means to the control of the discharge of liquefied gases considerably below room temperatl'ire, certain dificultiesare encountered which are not met with in plants operating at or above atmospheric temperature. These dimculties are mainly due to accumulation of small quantities of carbon dioxide and particularly of moisture which in freezing cement parts of an apparatus together'and render any mechanism inoperative.

One object of the present invention-is to provide a mechanism for automatically discharging liquefied gases from a vessel below atmospheric temperature with minimum danger of becoming inoperative by freezing of moisture upon it.

Another object of the invention is to provide a mechanism which can be easily freed from such frozen moisture. r

Another object of the invention is to provide means for freeing the mechanism, operated'manually from outside the thick layer of insulating material which necessarily covers these low temperature vessels to reduce heat leak into them from' the atmosphere.

Anotherobject of the invention is to manually control the discharge of liquefied gases whenever that may be desirable under abnormal operating conditions of plant or when the automatic control mechanism is inoperative for any reason.

. the rate of discharge.

1935, Serial No. 35,825 (01. 62-1 3 Another object of the invention is to arrange for movement of the vessel from which liquefied gases are discharged, with contraction and expansion of the plant due to cooling and heating.

Another object of the invention is to facilitate 6 defrosting the mechanism for discharge of liquefied gases. I

The foregoing, together with such other advantages as hereafter appear or are incident to the invention,"arerealized by the construction illusl0 trated in preferred form in the drawing, wherein Fig. 1 shows a cross-sectional elevation of the complete apparatus and Fig. 2 shows a modification of one detail thereof.

Referring to Fig. 1, the vessel in which a nearly 10 constant liquid level is to be maintained by discharge of liquefied gases therefrom has a metal wall I Two flexible pipes 2 and 3, one above the liquid level 4 and the other below this level, connect vessel l to auxiliary vessel 5. The liquid 20 level within vessel 5 will be the same as in vessel I except for frictional resistance to fiow of the liquid through pipe 3 and the presence of gas bubbles in either vessel.

The mechanism for controlling the discharge of liquefied gases automatically and manually is attached to auxiliary vessel 5. The head 6 is bolted to flanges l of vessel 5. An inclined passage-way 8 extends through the partition in head, 6' from the space within vessel 5 to the space into which the liquefied gases are to be dis charged. v

At the lower and inner end of passage-way 8 is a fiat narrow circular seat on which valve disk 9 rests when float I 0 is not buoyed up by liquefied gases within vessel 5. When the liquid level of the liquefied gases rises within vessel 5, float III also rises and lifts valve 9 from its seat, being attached thereto by the bent lever ll pivoted at l2.

The.,upper and outer end of passage-way. 8 has a conical seat for valve I3. A pin ll projects from valve l3 part way through passage-way 8. When valve 13 approaches its seat-at the outer.

end of passageway 8, pin l4 enters the depression 4 shown, in valve disk 9 and forces this valve disk away from its seat the inner end of passage-way 8. Thus, valve l3 must be wide open for valve 9 to be nearly closed and automatically control the discharge of liquefied gases from vessel 5 in order to maintain a nearly constant liquid level therein. When valve [3 is nearly closed to manually control the discharge .of liquefied gases, valve 9 is forced open so wide as to have little effect upon,

The liquefied gases dis 5 The stem N5 of valve l3 extends upwards through inclined sleeve l1. This sleeve is'held rigidly in place on head 6 by nut l8. At the outer end of sleeve I1 is a packing box with gland and nut for holding packing material l9 between sleeve l1 and stem IE to prevent leakage of home-- fled gases along the annular space between sleeve and stem.

Beyond the packing nut on the outer end of sleeve [1, stem it of valve I3 is enlarged at 29 and threaded to engage nut 2! which is held in place by yoke 22 attached to sleeve ll. Handwheel 23 is mounted on the end of stem I6.

Casing 24 holds heat insulating material 25 around vessels l and 5 and other parts of the apparatus shown. Sleeve l'l extends through insulating material 25 from head 8 at very low temperature to packing material l9 and yoke 22 at about atmospheric temperature. In order to reduce heat leak from the atmosphere through stem l6 and sleeve I! to the liquefled gases discharged from vessel 5, both stem and sleeve are made of a solid solution of copper and nickel which has considerably less heat conduc-- tivity than either metal in its pure state. This is in general true for all solid solutions. This particular solid solution has the further advantage that it does not rust or corrode in moist air.

duce conduction of heat along the stem.

Pipe 28 extending through insulating material 25 from head 8 to valve 21 outside of casing 24, is a drain pipe for the space into which the liquefied gases are discharged through passage-way 8.

In Fig. 2, the corresponding parts have the same numbers as in Fig. 1. The passage-way},

however, extends horizontally through the partition in head 6. Valve stem l8 and sleeve H- are also in horizontal positions. Valve I3 is arranged not only to seat upon the outer end of passageway 8 when moved to the left, but also to seat upon the inner end of sleeve I! when moved to theright into the position shown. In the position shown, leakage of liquefied gases is prevented between stem and sleeve irrespective of the tightness of any packing material at the outer end of sleeve II. In case such a back seating valve is employed for manual control of discharge of liquefied gases, there will be no advantage in enlarging the stem at the outer end as shown at 28 in Fig. 1.

During normal operation of a plant for rectify.- ing atmospheric air and equipped with 'automatic and manual controls for discharge of the liquefied shown in Fig. 1. or Fig. 2, the manually operated valve would be withdrawn from the outer, end of the passage-way 8 for discharge of liquefied. gases as shown in these two figures. The dis-- charge of liquefied gases would then be automatically controlled by the valve and float-lever mechanism shown, so as to maintain a nearly constant liquid level of the liquefied. gases within vessels I and 5. Should the rate of accumulation I or decrease, the liquid level would slightly riseor of passage-way 8 would be just sufllcient'to discharge the liquefied gases at they accumulate.

During normal operation of the plant, there is little danger of the automatic control mechanism sticking in any one position. -But should this occur, handwheei 23' can be rotated to move valve charged i'rom vessel 5 leave the apparatus through ing valve fall until the opening I between'valve 9 andthe seat at the inner end the same rates as l3 towards its seat at the outer end of passageway 8 until pin l4 engages the depression in valve disk 9 and forces the disk to move away from its seat at the inner end of passage-way 8. As soon as the mechanism is thereby freed of its sticking, manually controlled valve l3 may be withdrawn.

When theplant is shut down for defrosting,

I accumulated liquids may be withdrawn through the various drain pipes and valves provided for the purpose. Liquid in tube l5 and the space surrounding valve l3 may be withdrawn through drain pipe 28 and valve 21.

While moisture is being removed by blowing warm air through the plant, drain valve 21 may remain open until the air blowing out of it feels warm, thus indicating all moisture to be removed from pipe l5 and the space surrounding valve l3. If the space 'within vessel I isunder pressure, valve 9 will be forced against its'seat. By manual operation of valve l3, valve 9 can be forced from its seat by pin I4, thereby permitting warm air in vessel I to blow through vessel 5 and dry the float-lever mechanism therein.

With the construction shown in Fig. 1, valve l3 and stem it can be completely withdrawn through sleeve l1 and nut 2|. Warm air from pipe l5 will then blow through sleeve I1 and dry it. By inserting a small diameter rod through nut 2| and sleeve I1, valve 9 may be pushed away from its j seat to permit warm air within vessel l to blow Stem I6 is made hollow as shown to further rethrough sleeve ll. Valve l3 and stem Hi can then be replaced and repacked if necessary, ready for starting theplant when satisfactorily defrosted. All this can be done without disturbing insulating material 25.

Should the drying not be thoroughly done, but some moisture remain between valve 9 and its seat or even in the bearings at l2, this moisture will freeze upon recooling the plant to operating temperatures. The float-lever mechanism ll would then be held rigid by ice in the bearings at l2 and between valve 9 and its seat, thus rendering valve 9 inoperative. By manually operatl3, pin ll can be pushed against valve disk 9, thereby forcing this valve from its seat and breaking the bond of ice between valve 9 and its seat and also breaking any ice bond in the bearings at l2. The bearings at l2 should be made a loose fit to enable the latter to be easily done. The seat of valve 9 is made flat and narrow to provide little surface for holding moisture. Valve disk 9 has a depression facing passage-way 8 for pin to engage in forcing valve 9 from its seat. I

During normal operation, there is a tendency for liquefied gases surrounding valve 19 to flow along the annular space betwen stem l8 and sleeve II. The outer ends-of stem l9 and sleeve II are nearly at atmospheric temperature and of the liquefied gases at theinner end.- -Any liquefied gases flowing along stem I 8 and sleeve H to a region of higher temperature will absorbheat therefrom, vaporize and return to valve l9. circulation would materially increasebeat leak into the plant with corresponding loss of efiiciency. Two different methods of avoiding such loss are shown in Fig. 1 and Fig. 2.

In Fig. 1, sleeve I1 is inclined in extending through insulating material 25 and stem it passes upwards from valve llthrough sleeve II. Withpacking material l9 making a gas tight joint between sleeve [1 and stem ii, there is no flow pipe l5. The inclined of gas longitudinally. The gases in the annular space between sleeve l1 and stem it remain stagnant; Conduction of heat along sleeve and stem vapcrizesa small amount of liquefied gases at valve I3, and this vapor must escape through pipe IS, The liquid level of the liquefied gases therefore remains at the level of the outlet to position of sleeve l1 and stem It prevents liquefied gases entering the annular space between them. This construction therefore eliminates abnormal heat leak due to vaporization of liquefied gases flowing longitudinally between sleeve and stem. The inclined position of sleeve l1 and stem 16 necessitates an equal inclination of passage-way 8 -for pin It to project therethrough.

In Fig. 2 flow of liquefied gases into the annular space between sleeve l1 and stem l6 is'prevented by valve l3 back seating upon the end of sleeve I! when it is moved as far as possible to the right to the position shown. Sleeve l1 and stem It may then be in ahorizontal position with a simpler construction of head 6.

In any case, head 6 could be directly attached to vessel I instead of toauxiliary vessel 5. The latter arrangement, however, enables the manual control handle 23 to be more conveniently lo- 'cated. Thus, auxiliary vessel 5 may be placed for the most convenient location of handle 23 and pipes 2 and 3 run to vessel I, the restrictions being that auxiliary vessel 5 must be atthe proper level and pipes 2 and 3 must extend above and below the desired liquid level respectively, preferably without liquid or vapor traps. Then, as vessel I moves up and down by reason of expansion and contraction due to temperature changes in the plant, this movement may be taker: care of by making pipes 2 and 3 sufilciently long and flexible, auxiliary vessel 5 being supported in a position substantially fixed relative to casing 24 through which sleeve l1 projects.

Passage-way 8 may be formed of a removable bushing to facilitate repairs.

I claim: 1. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material, including a partition between the space within said vessel and the space into which said liquefied gases are discharged, a passage-way through said partition, a valve and seat at the innerend of said passage-way, means for opening and closing said valve with rise and fall in the level of said liquefied gases, a second valve and seat at the outer end of said passage-way, a sleeve through said insulating material and a stem from said second valve-extending through said sleeve for manually operating said second valve outside said insulating material. H

2. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material as in claim 1, including means for holding the first valve off its seat when said second valve is nearly closed. 3. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material as in claim 1, including a pin projecting from the manually operated valve through said passage-way whereby the valve at the inner end of said passageway is held ofi its seat when the manually operated valve is nearly closed. v

4. Apparatus for discharging liquefied gases from'a vessel below atmospheric temperature and covered with insulating material as in claim 1, including packing material between said sleeve and said stem to prevent leakage of said liquefied ases.

5. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating'material as in claim 1, including a seat on the inner end of said sleeve for said second valve whereby leakage of said liquefied gases between said sleeve and said stem -may be prevented by closing said second valve on .of a solid solution of metals having lower heat conductivity than pure metals.

7. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material as in claim 1, wherein said stem is made hollow to reduce conduction of heat along said stem.

8. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material as in claim 1, including an enlarged part of said stem with threads thereon beyond said sleeve, and a. nut engaging said threads and held by a yoke to said sleeve whereby said valve is opened and closed by rotating said stem and said stem can be removed through said nut.

9. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature, and covered with insulating material, including a partition between the space within said vessel and the space into which said liquefied gases are discharged, a passage-way through said partition, a valve and seat at the inner end of said passage-way, means for opening and closing said valve with rise and fall in the level of said liquefied gases, and means extending through said heat leak is reduced" liquid level of said liquefied gases within said vessel, and a manually operated valve seating at the outer end of said passage-way, wherein said disk valve has a depression therein and a pin projects from the manually operated valve into said depression to hold the disk valve open when the manually operated valve is nearly closed.

11. Apparatus for discharging liquefied'gases from a. vessel below atmospheric temperature and covered with insulating material; including a partition between the space within said vessel and the space into which said liquefied gases are discharged, an inclined "passage-way extending upwards through said partition, a valve and seat.

at the lower end of'said passage-way, means for opening and closing said valve with rise and fall in level of said liquefied gases, a second valveand seat at the upper end of said passage-way, an in-' clined sleeve through said insulating material, a stem from said second valve extending upwards through -said sleeve for manually operating said second valve, and packing material between said sleeve and said stem to prevent leakage of said liquefied gases.

12. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material as in claim 11, including means for holding the first valve off its seat when said second valve is nearly closed.

13. 'Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material, including a partition between the space within said vessel and the space into which said liquefied gases are discharged, an inclined passage-way extending upwards through said partition, a valve and seat at the lower end of said passage-way, means for opening and closing said valve with rise and fall in level of said liquefied gases, a second valve and seat at the upper end of said passage-way, an inclined. sleeve through said insulating ma.- terial, a stem from said second valve extending upwards through said sleeve for manually operating said second valve, packing material between said sleeve and said'stem to prevent leakage of said liquefied gases, and a pin projecting from said second valve through said passage-way whereby the first valve is held ofi its seat when said second valve is nearly closed.

14. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material, including a artition between the space within said vessel and the space into which said liquefied gases are discharged, an inclined passage-way extending upwards through said partition, a valve and seat at the lower,end of said passage-way, a float partly immersed in said liquefied gases, a lever connecting said valve and said float whereby a rise or fall of said float with the level of said liquefied gases opens or closes said valve, a second valve and seat at the. upper end or said passageway, an inclined sleeve through said insulating material, a stem from said second valve extending upwards through said sleeve for manually operating said second valve, packing material between said sleeve and said stem to prevent leakage of said liquefied gases, and a 'pin projecting from said second valve through said passage-way whereby the first valve is held ofi its seat when said second valve is nearly closed.

15. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material, including a partition between the space within said vessel and the space into which said liquefied gases are discharged, an inclined passage-way extending upwards through said partition, a valve and seat at the lower end of said passage-way, a float partly immersed in said liquefied gases, a leverfconnecting said valve and said float whereby a rise or fall or said float with the level of said liquefied gases opens or closes said valve, a second valveand seat at the upper end oi! said passage-way, an inclined sleeve through said insulating material, a stem from said second valve extending upwards through said sleeve for manually operating said second valve, packing material between said sleeve and said stem to prevent leakage of said liquefied gases, an enlarged part of said stem with threads thereon beyond said sleeve, a nut engaging said threads and held by a yoke to said sleeve whereby said second valve is moved longitudinally by rotating said stem and said stem may be removed through said nut, and a pin projecting from said second valve through said passage-way whereby the first valve is held off its seat when said second valve is nearly closed.

16. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature, including a partition between the space within saidvessel and the space into which said liquefied gases are discharged, a passage-way through said partition, a valve seating at the inner end of saidpassage-way, means for operating said valve by variations in liquid level or said liquefied gases within said vessel, a manually operated valve seating at the outer end of said passage-way and ineluding means for holding the first mentioned valve ofl its seat when the manually operated.

valve is nearly closed whereby variations in liquid level of said liquefied gases within said vessel are controlled by said manually operated valve.

17. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material, including a casing surrounding said insulating material, an aux- -iliary vessel fixed relative to said casing, means for varying the rate of discharge or said liquefied gases from said auxiliary vessel, means for operating the same from without said insulating material, and flexible connections between the first mentioned vessel and said auxiliary vessel for flow of liquid and vapor to said auxiliary vessel whereby the first mentioned vessel may move upand down relative to said casing by reason or expansion and contraction due to temperature changes.

18. Apparatus for discharging liquefied gases from a vessel below atmospheric temperature and covered with insulating material, including a partition between the space within said vessel and the space into which said liquefied gases are discharged, a passage-way through said partition, a valve for closing said passage-way, a sleeve through said insulating material, a stem from said valve extending through said sleeve for manually operating saidvalve outside said insulating material, an enlarged part of said stem with threads thereon beyond said sleeve and a nut engaging said threads and held by a yoke to said sleeve whereby said valve is opened and closed by rotating said stem and said stem can be removed throughsaid nut.

- WILLIAM LANE DE BAUFRE. 

